Trend Analysis of Homicide Mortality and Years of Life Lost in the South of Iran, 2004-2019

Background: This study was conducted to determine the mortality rate and years of life lost (YLL) due to homicide in Fars province. Study Design: This was a cross-sectional study. Methods: All data related to deaths due to homicide in Fars province were obtained from the Populationbased Electronic Death Registration System. Crude and age-standardized mortality rate, YLL, and YLL rate data were calculated and joinpoint regression was used to examine the trend. Results: During 2004-2019, 2148 deaths due to homicide occurred in Fars province, and (1782 cases (83.0%) were men. The crude mortality rate in men decreased by 44.0% from 2004 to 2019, but a stable trend was observed in women. The total YLL due to homicide during these 16 years was 43230 (1.37 per 1000 people) in men and 8931 (0.29 per 1000 people) in women. According to the joinpoint regression analysis, the 16-year trend of the YLL rate due to premature mortality in men was decreasing, and the annual percent change (APC) was -4.00% (95% confidence interval [CI]: -6.60 to -1.20, P=0.008). However, women demonstrated stable trends in this respect, and APC was -0.50% (95% CI: -3.10 to 2.20, P=0.704). Conclusion: The crude and standardized mortality rates and the number of YLL due to homicide in the study period had a significant decreasing trend in men but a stable trend in women. To control this issue, officials and policymakers should identify the areas of homicide and control its risk factors such as economic and social issues, drug addiction, and the state of violence.

-are significant, ranging from a low in Japan (0.5 per 100 000) to over 50 per 100 000 in Côte d'Ivoire and El Salvador. 12 In Iran, all previous studies on homicide were cross-sectional and were performed over one year, and the trend of changes in the rate of homicide in the country has not been investigated so far. 13 The years of life lost (YLL) are an essential criterion for ranking the health status of society and observing their challenges. According to the report of the World Health Organization (WHO), the value of one year of life is three times more than the gross domestic product per capita of any country. 14 Considering that no study has so far focused on determining the YLL due to homicide in Fars province, this study sought to measure the mortality rate and YLL due to homicide in Fars province.

Methods
This cross-sectional study was conducted in Fars province from 2004 to 2019. The data relating to all homicide deaths were extracted from the population-based Electronic Death Registration System by age, gender, and year of death based on the International Classification of Diseases (10th revision). In the mentioned system, all available sources have been used to detect, record, and collect deathrelated information. Repeated deaths were excluded from the study based on the father's name and national number similarity. In addition, death cases suspected of homicide were excluded from the research, and only instances of definite homicide were included in the study.

Statistical analysis
First, crude and age-standardized mortality rates (ASR) of homicide were calculated during the study years according to gender and the year of death. To calculate the crude mortality rate, the average population of Fars province was employed for each year. The standard population in 2013 for low-and intermediate-income countries was applied for standardization.
Then, to calculate YLL, the standard life table was used, and life expectancy was determined for different age and gender groups, as well as the number of deaths due to homicide in each age and gender group based on the following relationship 15 : 16 Where N represents the number of deaths of a particular gender and age. In addition, N is the standardized life expectancy of the deceased at the same age and gender. Further, R and β are the discounting rate (0.03) and the contractual rate in calculating the age value (0.04), respectively. Furthermore, C is an adjusted fixed value (0.1658). Finally, a denotes the age at which death occurred and e is constant (2.71).
The number of YLLs due to premature death due to homicide was analyzed using the YLL template of 2015, the WHO, in Excel spreadsheet software, version 2016.
Joinpoint regression based on the log-linear model was used to examine the trend of crude and standardized mortality rates and YLL rates for different years. It describes changing trends over successive segments of time and the number of increases or decreases within each piece. The resulting line segment between joinpoints is defined by the annual percent change (APC) based on the line segment's slope and the average annual percent change (AAPC). Joinpoint Regression Program 4.9.1.0 performed the analysis for the trend.
The protocol of this study was reviewed and approved by the Ethics Committee of Shiraz University of Medical Sciences (Code: IR.SUMS.REC.1399.772). All study aspects were conducted according to the university's code of ethics.
The highest and lowest deaths in both genders were in the age groups of 15-29 years and less than 5 years, respectively ( Figure 1).

Temporal trends of homicide mortality by age groups
In the 0-44 age group, the homicide mortality rate had a decreasing trend in men (AAPC = -3.50%, P = 0.043), while a stable trend was observed in women (AAPC = -1.90%, P = 0.387).

Temporal trends of homicide YLL rate
The total YLL due to homicide during the 16-year study period was 43 230 (1.37 per 1000 people) in men and 8931 (0.29 per 1000 people) in women, and overall, 52 161 (0.83 per 1000 people) in both genders (men/women gender ratio, 4.84, Table 1). The average number of YLLs due to homicide was 24.3 and 24.4 years for men and women.
The highest and lowest YLL in both genders were observed in the age groups of 15-29 years and under 5 years, respectively ( Figure 2).
According to the joinpoint regression analysis, the 16year trend of the YLL rate due to premature mortality in men was decreasing. The APC was -4.00% (95% CI: -6.60 to -1.20; P = 0.008) and there were stable trends in women. According to the join point regression analysis, the 16-year trend of YLL rate due to premature mortality in men's was decreasing. The APC was -4.00% (95% CI -6.60 to -1.20, P = 0.008) and stable trends in women, APC was -0.50% (95% CI -3.10 to 2.20, P = 0.704) and decreasing trend for both sexes (total), APC was -3.40% (95% CI -5.80 to-0.90, P = 0.012). The model did not demonstrate any joinpoint; hence, the AAPC was the same as APC (Figures 3 and 4).

Discussion
The current study was conducted with the aim of investigating the mortality rate and YLL due to homicide in  Fars province during 2004-2019. According to the authors, this study is the first one to examine the mortality rate and YLL due to homicide in 16 years in Iran. The results of this study showed that the crude and standardized mortality rates due to homicide in men decreased significantly from 2004 to 2019, while it had a stable trend in the same period of time in women. Moreover, the number of total YLLs due to homicide was higher in men than in women. The highest number of YLLs in both genders was in the age group of 15-29. The trend of the years of YLL homicide represented a decreasing trend in men, whereas it was stable in women. In a study conducted by Peres et al, the trend of the mortality rate due to homicide in different cities of the country was heterogeneous. Although there was a decreasing trend in some cities, an increasing trend was observed in other cities. 17 20 Therefore, homicide has different trends in various countries. Although violence appears to be a humanized, universal phenomenon, there is a great

Age groups
Male Female variation in the amount of violence in every society at a certain time. In some societies, violent attacks account for up to 60% of all deaths, and in other countries, they account for less than 0.05% of all deaths. 16 In the present study, the mortality rate due to homicide was 5.7, 1.2, and 3.5 (per 100 000) in men, women, and both genders, respectively. Based on the results of another study, 12 the homicide rate was 2.04, 11.73, and 17.45 in countries with high, medium, and low human development indexes (HDI), respectively (per 100 000). Compared to the findings of the study, the mortality rate due to homicide in Fars province was lower than in countries with a medium and low HDI, but higher than in continents with a high HDI. According to the reports of various studies in Iran and other countries regarding studying homicide, various factors such as gender, age, psychiatric disorders, climatic and ecological conditions, socio-economic level, cultural factors, poverty, individual violence, and family breakdown are involved in this regard. 10,13,21 Nazari et al 13 reported that the highest number of deaths and mortality due to homicide was in the age group of 15-29, and the crude and standardized rate of death was higher in men than in women, which is in line with the results of the current study. In our study, the highest number of deaths due to homicide was in the age group of 15-29, and the mortality rate was higher in men than in women. The existence of laws related to the prevention of all types of violence, including child abuse laws, laws against child marriage or the legal age of marriage for women or men, youth violence laws against school-licensed weapons or membership in gangs or criminal groups, sexual violence laws against sexual assault, victim laws, and compensations offered to victims, can affect the reduction of homicide in Fars province. 13 In a study conducted by Zavala-Zegarra et al, a constant trend was observed in the annual mortality rate due to homicide in men from 2001 to 2007 (APC = -0.80%), but this trend had a significant increase from 2007 to 2010 (APC = 11.10%). However, there was a non-significant constant trend during the ten-year study period in women (APC = -1.40%). 22 Conversely, the results of this study contradict those of our study on the trend of the annual rate of homicide in men, which is consistent with this trend in women. In the current study, the mortality rate due to homicide in men significantly decreased during the 16-year study period (APC = -3.80%), but this trend was stable in women (APC = 0.30%). A progression in different aspects of health care, including the development of emergency and trauma care systems, may also play a significant role in decreasing homicide-related death rates. Differences in the biological features of males and females are described as the reasons for this trend. 23 In another study conducted in Iceland, 24 the rate of YLL due to homicide was 50.4 per 100 000, which is lower than the results of our study (83 per 100 000). Veisani et al evaluated the YLL due to homicide during 2014-2018 and found that YLL due to homicide was more considerable in men and the age group of 15-29, 25 which conforms to the results of our study. Homicides as a proportion of violent death remain high among younger age groups but abruptly decreased after the age of 45 years. Therefore, specific strategies to prevent gun violence are important to reduce the burden of violence. For example, when implemented well, street outreach strategies for high-risk youth in urban areas have shown promise for reducing gun violence. 26 The findings of this study demonstrated that the YLL measure can assess the burden of homicide and the effectiveness of efforts in the prevention of violent death. If resources are limited, YLL may especially help policymakers target premature death subpopulations and set top priorities for programs related to the prevention of violent death. 24 This study had some limitations. YLL was not evaluated throughout the whole of Iran due to the unavailability of the necessary data. The possibility of the incompleteness of the death registration system, as well as the misclassification of the death registration, could have affected the results of the study. The joinpoint regression is done as an ecological study. Moreover, multivariate analyses could not be yielded from the joinpoint regression program. On the other hand, this study was of high quality and had a strong study design, a large sample size, and the extensive time period of data analysis.

Conclusion
The crude and standardized mortality rates and the number of YLL due to homicide in the study period had a significant decreasing trend in men, but a stable trend in women. Although the decreasing trend in homicide in Fars province is good, it is not yet enough. To control this issue, officials and policymakers should identify the areas of homicide and control its risk factors such as economic and social issues, drug addiction, and the state of violence. Poverty, unemployment, social inequality, and incorrect tribal traditions are the other risk factors. To prevent youth violence, counseling, vocational training, family therapy, training health care workers in order to identify and refer youth at risk of violence, and policies pertaining to the reduction of the adverse effects of rapid social changes and dealing with gun violence among the youth are the other effective factors.